1592 HUNT THE PREPARATION OF ETHYL IODIDE. CLXXV1.-The Preparation of Ethyl Iodide. By BEATRICE ELIZABETHA HUNT. THE preparation of ethyl iodide has recently been investigated by Adams and Voorhees ( J . Amer. Chent. SOC. 1919 41 789)) who recommend the employme'nt of Walker's method (T. 1892 61, 717) in a slightly modified form. An alternative method how-ever appeared possible in view of the work of Beilstein and Rieth (Annalen 1863 126 250) and this process forms t,he subject of the present communication HUNT THE PREPARATION OF ETHYL IODIDE. 1593 Experiment showed that with the use of 80 per cent alcohol in place of absolute alcohol the vigour of the reaction caused by the addition of iodine was so much reduced that the time required to mix 500 grams of iodine with the requisite amount of alcohol and red phosphorus was not more than twenty minutes.Further the yield was not affected by the omission of the customary period of keeping a t the ordinary temperature but boiling under reflux for two and a-half hours followed by immediate distillation was sufficient to' ensure a good yield. The use of a large excess of alcohol is often suggested but this proved unnecessary and indeed, rendered the process of purification niore difficult and thus reduced the yield. I n most modern text-books the iliain reaction is regarded as taking place according to tlis equation P + 31 + C2H60 = 3C,HjI + P(OH),, but Beilstein (loc. c i t . ) interprets it thus: P + 51 + C,H,O = 5CzI151 + H,PO 3- H20. Estimations of the amount of unused phosphorus remaining after distillation agreed with this interpretation which was further verified by the preparation of ethyl iodide using the amount of phosphorus required by Beilstein's equation when a good yield was obtained.I n practice however it proved better to use an excess of phosphorus to ensure purity of the product. E S I' E R I M E N T A Id. To 500 grains of iodine in a flask of 4 litres capacity cooled by water about 281 grains of 80 per cent. alcohol (by weight) were: added and thereafter during the course of about twenty minutes, 50 grams of red phosphorus with shaliiiig after each addition to ensure complete mixing. The first additions of phosphorus caused evolution of heat and boiling of the1 liquid in tho flask but no loss of vapour occurred.A reflux condenser was then attached to the flask and the latter heated in a water-bath so that the contents boiled gently. After about two and a-half hours iodine vapour was no longer visible although the mixture remained dark in colour. The ethyl iodide was without cooling distilled off through a short two-bulb condensing column by heating first in a watar-bath and aft,erwards an a brine-bath. All the distillate passed over a t 63-43' and was colourless except for a small fraction a t the end which had a yellow tinge. A few drops of sodium carbonate solution were added t o ensure absence of free hydriodic acid and a few drops of a dilute solution of sor7iun1 thiosulpliat 1594 GREENWOOD AND NIERENSTSIN : to remove any free iodine since ethyl iodide purified with sodiuni t$hiosulphate was proved to darken less quickly on keeping than when sodium carbonate alone was used and the purification was accomplished more rapidly. The oil was then washed with water, dried over calcium chloride and redistilled. The yield was 566 grams (92 per cent. of 'the theoretical) and the unused red phosphorus amounted t~ 24.45 grams. UNIVERSITY COLLEGE, SOUTH AMPTON. [Rm-iued October 2tith 1920.